A new study from McGill University has found that a simple blood test could help predict the risk of developing dementia years in advance for people with a specific sleep disorder.
This discovery could open the door to earlier diagnosis, better planning, and possibly more effective treatments for certain types of dementia.
The sleep disorder in question is called Idiopathic REM Sleep Behavior Disorder (iRBD). It causes people to physically act out their dreams during deep sleep.
While this may sound unusual or even harmless, iRBD is actually a major early warning sign for serious brain conditions.
People with this disorder have a much higher risk of developing Parkinson’s disease or Dementia with Lewy Bodies (DLB)—a form of dementia that affects memory, thinking, movement, and often causes vivid hallucinations.
In the new study, researchers followed 150 people diagnosed with iRBD and tested their blood for certain proteins called biomarkers—specifically, two proteins known to be linked with Alzheimer’s disease.
These proteins are called phosphorylated tau and amyloid beta, and their presence in the blood can signal changes in the brain long before any cognitive symptoms appear.
Over a four-year period, the researchers checked in on the participants annually to see how their health progressed. The results were striking: the blood test accurately predicted dementia in nearly 90% of the people who eventually developed it.
This finding is especially important because DLB and other neurodegenerative diseases often go undiagnosed until symptoms are already advanced.
“Detecting dementia risk early could have significant implications for how doctors guide patients,” said Dr. Ronald Postuma, senior author of the study and professor in the Department of Neurology at McGill University. “It could help people plan for the future and may even allow us to offer personalized and more effective treatments.”
The research, published in the journal Brain, also suggests there may be more overlap between Alzheimer’s, Parkinson’s, and Lewy Body dementia than previously believed. Because the test used Alzheimer’s biomarkers but successfully predicted a different kind of dementia, scientists now suspect these brain diseases might share common early warning signs.
According to Dr. Aline Delva, the study’s lead author, this opens up exciting new possibilities: “Our findings suggest that Alzheimer’s treatments could also be tested in patients with this sleep disorder. Perhaps, if treatments start early enough, we could even prevent the development of Dementia with Lewy Bodies.”
Right now, there is no cure for DLB or Parkinson’s, and treatments mostly manage symptoms. By the time memory loss or movement problems appear, significant damage has often already been done to the brain.
A blood test that can predict risk years before symptoms start could shift the timeline—allowing for earlier interventions, better monitoring, and more targeted therapies.
The study is especially significant because blood tests are far easier, cheaper, and less invasive than brain scans or spinal taps, which are currently used to detect brain diseases in some cases.
The research team plans to expand the study to include people already diagnosed with Parkinson’s and other high-risk groups. The goal is to see if the blood test can predict dementia risk in these populations as well.
If future research confirms the findings, this test could one day become part of regular check-ups for people with iRBD or early Parkinson’s symptoms—giving doctors and patients a head start in managing what are currently life-altering diseases.
For now, the study is a hopeful step forward in the fight against dementia, showing that the key to prevention may lie in detecting the earliest silent changes in the brain—and that a simple blood test could make that possible.
If you care about dementia, please read studies about dietary strategies to ward off dementia, and how omega-3 fatty acids fuel your mind.
For more health information, please see recent studies about Choline deficiency linked to Alzheimer’s disease, and what to eat (and avoid) for dementia prevention.
The research findings can be found in Brain.
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